THE USE OF A NEW RADIOACTIVE-IODINE LABELED LIPID MARKER TO FOLLOW INVIVO DISPOSITION OF LIPOSOMES - COMPARISON WITH AN ENCAPSULATED AQUEOUS SPACE MARKER

  • 1 January 1982
    • journal article
    • research article
    • Vol. 37  (2) , 199-213
Abstract
The in vivo disposition and multilamellar liposomes extruded at 0.6 .mu.m (PC/DPPA/CH/.alpha.-T [phosphatidylcholine/dipalmitoyl phosphatidic acid/cholesterol/.alpha.-tocopherol] = 4:1:5:0.1 molar ratio) when injected i.v. into mice was examined with a novel iodinatable phospholipid derivative used as a lipid phase marker (p-hydroxybenzamidine phosphatidylethanolamine, 125I-BPE), and with 14C-inulin used as an aqueous phase marker. At times up to 5 h postdose, the disposition of both markers was essentially identical, except in the blood and intestine, where 125I-BPE levels were consistently higher than the 14C-inulin levels. At time intervals from 5-72 h postdose, 125I-BPE levels in all the organs examined were lower than the 14C-inulin levels. These differences in the behavior of the 2 labels may be explained in terms of exchange of the iodinated lipids, excretion of released inulin and long-term metabolism of the lipid marker. Apparently, 125I-BPE is a useful marker for following liposome disposition in short-term studies, particularly because of the easily quantifiable nature of .gamma.-radioactivity which obviates the need for sample preparation.

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